This invention relates to video signal processing for freezing one picture frame or field of motion pictures to obtain a still picture on a television receiver, and particularly to a circuit capable of producing a still picture of high quality in a system having a small memory capacity.
A television receiver is known in which a video signal is digitized and processed in digital form to additionally provide a variety of new functions.
One of the functions is that one frame or field of a motion picture displayed on the faceplate of a cathode-ray tube of a television receiver may be displayed as a still picture. This function of converting from motion pictures to a still picture is referred to as a frame freezing, still frame or stop action.
In order to create the freeze function, a memory is needed for storing a digital video signal of one field or one frame. This field or frame memory is described in "Applications of Picture Memories in Television Receivers", IEEE Transaction on Consumer Electronics, Vol. CE-29, No. 3, August, 1983, by E. J. Berkhoff, et al.
A memory capacity M for storing one field of video signals can be expressed as ##EQU1## assuming that the clock frequency is 4 f.sub.sc (14.32 MHz, f.sub.sc is the color subcarrier frequency), the horizontal scanning frequency is 15.75 KHz, the number of horizontal scanning lines per field is 525/2, and the quantized bit number is 8. From this expression it will be understood that a memory of a very large capacity is necessary for storing one field of a video signal.